1. Field of the Inventions
The present inventions relate to an steering system for a small boat, and in particular, to electric steering systems for boats.
2. Description of the Related Art
Japanese Patent No. JP-B-2959044 discloses a steering system for a watercraft using an electric motor in place of a hydraulic mechanism, for steering an outboard motor-powered small boat. This electric steering system is adapted such that the electric motor is driven by an electric current command signal corresponding to a turning angle of a steering wheel based on operator's steering wheel operation, to rotate the outboard motor for steering.
In this electric-motor-driven steering system, however, since the electric motor is driven via an electric cable from the steering wheel, the steering wheel is not returned to its center position after the operator operates it to change the running direction of the boat. This requires the operator to return the steering wheel, providing less satisfactory operability.
Further, the outboard motor is better drained when stored with the body placed in the center position within its turning range about the swivel shaft, which is preferable for transportation. It is thus necessary to return the outboard motor to its center position after docking. However, the conventional electric steering system for an outboard motor is adapted such that it is not operable when the engine is stopped and power is turned OFF. The operator, therefore, is required to return the outboard motor to its center position before he/she turns the power OFF, which takes time and effort. If the operator forgets to return the motor to the center position before shutting down the engine, the operator must restart the engine long enough to turn the motor, then again powered down the engine.
Further, in the case that the engine is stopped by an emergency or “auxiliary” stop switch such as a safety switch during cruising at high speed, the motor and propeller will stop immediately, but the steering angle of the motor will not change. Thus, if this occurs during a turn, the boat will continue to coast with the outboard motor, acting as a rudder, disposed at a turning angle. Thus, the boat will coast into a turn; potentially giving the operator and/or passengers an uncomfortable feeling.
Japanese Patent Publication No. 2002-331948 discloses an electric power steering system for a land vehicle with an assist motor which returns the wheels and steering wheel to their center positions after the driver turns the steering wheel. This land vehicle vehicular power steering system controls steering motion when the vehicle is running and when the engine is driven with a main switch ON. However, this system does not operate at all, nor does it need to work when the engine is stopped.